L2 Announcement

L2 Announcements is a feature which makes services visible and reachable on the local area network. This feature is primarily intended for on-premises deployments within networks without BGP based routing such as office or campus networks.

When used, this feature will respond to ARP/NDP queries for ExternalIPs and/or LoadBalancer IPs. These IPs are Virtual IPs (not installed on network devices) on multiple nodes, so for each service one node at a time will respond to ARP/NDP queries and respond with its MAC address. This node will perform load balancing with the service load balancing feature, thus acting as a north/south load balancer.

• Can be used to advertise L2 (MAC) addresses
• No need to run BGP
• Nodes will respond to arp requests for IP addresses of services

Enable L2 Announcement

kubeProxyReplacement: true
l2Announcements:
  # -- Enable L2 pod announcements
  enabled: true

After enabling L2 accouncements, create a policy (Policies provide fine-grained control over which services should be announced, where, and how.):

apiVersion: "cilium.io/v2alpha1"
kind: CiliumL2AnnouncementPolicy
metadata:
  name: policy1
spec:
  serviceSelector:
    matchLabels:
      color: blue
  nodeSelector:
    matchExpressions:
      - key: node-role.kubernetes.io/control-plane
        operator: DoesNotExist
  interfaces:
  - ^eth[0-9]+
  externalIPs: true
  loadBalancerIPs: true

Useful commands

$ kubectl -n kube-system get lease